Mathematics 9709 · AS & A Level · Coordinate geometry

Coordinate geometry — practice question

The diagram depicts a solid figure $OABCDEF$ with a horizontal rectangular base $OABC$, where $OA = 6$ units and $AB = 3$ units. The vertical edges $OF$, $AD$ and $BE$ measure $6$ units, $4$ units and $4$ units respectively. The unit vectors $\mathbf{i}$, $\mathbf{j}$ and $\mathbf{k}$ are parallel to $OA$, $OC$ and $OF$ respectively.
(i)[1]

Find the vector $\overrightarrow{DF}$.

(ii)[3]

Find the unit vector that points in the direction of $\overrightarrow{EF}$.

(iii)[4]

Use a scalar product to determine angle $EFD$.

Worked solution & mark scheme

This 8-mark question has a full step-by-step worked solution and mark scheme. One marking point: Hence, write $\vec{DF}=-6\mathbf{i}+2\mathbf{k}$.

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